/*
 * Copyright 2000-2014 JetBrains s.r.o.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.intellij.psi;

import com.intellij.openapi.diagnostic.Logger;
import com.intellij.psi.util.PsiUtilCore;
import com.intellij.util.WalkingState;
import org.jetbrains.annotations.NotNull;

/**
 * @author cdr
 */
public abstract class PsiWalkingState extends WalkingState<PsiElement> {
    private static final Logger LOG = Logger.getInstance("#com.intellij.psi.PsiWalkingState");
    private final PsiElementVisitor myVisitor;

    private static class PsiTreeGuide implements TreeGuide<PsiElement> {
        @Override
        public PsiElement getNextSibling(@NotNull PsiElement element) {
            return checkSanity(element, element.getNextSibling());
        }

        private static PsiElement checkSanity(PsiElement element, PsiElement sibling) {
            if (sibling == PsiUtilCore.NULL_PSI_ELEMENT)
                throw new PsiInvalidElementAccessException(element, "Sibling of " + element + " is NULL_PSI_ELEMENT");
            return sibling;
        }

        @Override
        public PsiElement getPrevSibling(@NotNull PsiElement element) {
            return checkSanity(element, element.getPrevSibling());
        }

        @Override
        public PsiElement getFirstChild(@NotNull PsiElement element) {
            return element.getFirstChild();
        }

        @Override
        public PsiElement getParent(@NotNull PsiElement element) {
            return element.getParent();
        }

        private static final PsiTreeGuide instance = new PsiTreeGuide();
    }

    protected PsiWalkingState(@NotNull PsiElementVisitor delegate) {
        this(delegate, PsiTreeGuide.instance);
    }

    protected PsiWalkingState(@NotNull PsiElementVisitor delegate, @NotNull TreeGuide<PsiElement> guide) {
        super(guide);
        myVisitor = delegate;
    }

    @Override
    public void visit(@NotNull PsiElement element) {
        element.accept(myVisitor);
    }

    @Override
    public void elementStarted(@NotNull PsiElement element) {
        if (!startedWalking && element instanceof PsiCompiledElement) {
            LOG.error(element + "; Do not use walking visitor inside compiled PSI since getNextSibling() is too slow there");
        }

        super.elementStarted(element);
    }
}
